This invention relates to a fluid flow diverter disc valve, particularly for use in the cleaning of tubing of heat exchangers.
It has previously been suggested that heat exchanger tubing may be internally cleaned by disposing brush-basket devices at the ends of the tubes, and then by flowing fluid first in one direction and then the other to cause the brushes to traverse the length of the tubes and then return to their original positions. See the above-identified U.S. Pat. No. 3,319,710.
It has also been previously suggested as in the above-identified U.S. Pat. No. 3,973,592 to utilize a four-way valve for purposes of reversing fluid flow within the tubes to cause the cleaning brushes to move in both directions within the tubes. U.S. Pat. No. 3,973,592 reduces or eliminates external piping and utilizes a series of fixed fluid flow chambers in combination with a butterfly type plug valve having a rotatable vane for directing the fluid through the chambers. This construction is rather complex and results in side thrust on the vane support bearings as well as requiring relatively high vane turning torque. There is also a fair amount of pressure drop through the valve and at least some penetration of high (or supply) pressure fluid into the area of low (or return) pressure.
The above U.S. Pat. Nos. 660,011, 925,692 and 1,339,284 disclose various types of rotary valves of interest. The construction of U.S. Pat. No. 660,011, due to the fact that the flowing fluid makes a number of U-turns within the valve which causes high velocity pressure, is subject to high turning torque and a substantial pressure drop through the valve. In U.S. Pat. Nos. 925,692 and 1,339,284, the flowing fluid is directed through the end members of the rotary unit, thus creating a high turning torque.
It is an object of the present invention to provide an improved 4-way fluid flow reversal valve of the type which eliminates external piping, and wherein side thrust on the rotary bearings and turning torque are reduced to a minimum.
It is a further object of the present invention to reduce the pressure drop through the valve to a minimum.
It is yet another object of the present invention to maximize sealing between the rotary and fixed parts to retard fluid under high pressure from penetrating into the area of low fluid pressure.
It is an additional object of the present invention to provide a 4-way valve which is relatively inexpensive and easy to manufacture, install operate and maintain.
In accordance with the various aspects of the present invention, a longitudinally extending housing is provided with a generally cylindrical side wall closed by opposed end walls. The housing side wall is ported, to connect with supply and return lines from a source of pressurized fluid, and also to connect with the input and discharge lines of a process loop. The housing contains a longitudinally extending rotary axle which forms a part of a valve rotator assembly adapted to be angularly positioned between a normal fluid flow position and a reverse flow position.
The valve rotator assembly includes a plurality of segmental arcuate pie-shaped portless discs mounted for rotation with the axle. The discs extend radially outwardly from the axle, and transversely to the axis defined thereby, and terminate closely adjacent the housing side wall. The discs are disposed alternately adjacent opposite ends of the axle, but spaced from their adjacent housing side wall. Axially aligned alternate disc edges are joined by radial longitudinally extending partitions to form a plurality of alternately axially oppositely facing rotary chambers adapted to communicate with the housing ports. Each chamber is delineated by a disc and two partitions, as well as the housing side wall, with the end of the chamber opposite the disc being open into the housing chamber.
The two pair of diametrically opposed discs form a pair of axially spaced transverse planes which are disposed adjacent but spaced from their respective housing end walls. The housing ports are confined between the planes. Due to the open chamber ends, diametrically opposed chambers are always connected through their said open ends via the housing chamber.
In the present embodiment, two diametrically opposed chambers are of generally equal arcuate extent and size, while the other diametrically opposed chambers are of differing arcuate extent and size with one chamber being of substantially lesser arcuate extent than the other. When the valve rotator assembly is in normal position, the lesser sized chamber is blocked and the diametrically opposed larger chamber registers with two ports. In the reverse position of the valve rotator assembly, the lesser size chamber and its diametrically opposed larger chamber each register with a single port. In both assembly positions, the diametrically opposed generally equal sized chambers each register with one port.
The construction provides that fluid flowing through the housing between ports is always directed across the disc faces parallel to the spaced planes, and flows through the housing generally diametrically.
The entire perimeter of the valve rotator assembly is sealed to the circumferential housing side wall by seals extending along the arcuate disc edges. These seals are positioned in the spaced planes with the housing ports disposed between the planes so that the seals fully engage the housing side wall at all times. In a second embodiment, longitudinal seals are additionally disposed along the outer longitudinal edges of the partitions.